In some dynamic X-radiography procedures such as peripheral angiography and venography it is necessary to support a human patient on a table and drive the table through the radiography zone of the X-ray beam so that the patient is radiologically examined nearly his full length from shoulders to ankles, but without moving the patient relatively to the table. Typically the patient receives an injection of radio-opaque dye at one point in his body and the progress of the head of the dye stream in veins up or down his body is recorded by a rapid succession of overlapping X-ray exposures. To insure that successive exposures overlap reasonably uniformly, a motorized or manual table drive mechanism is required. Metallic parts of the drive mechanism, being radio-opaque, must not extend into the radiography zone. On the other hand, because of space limitations in X-ray rooms the drive mechanism should not extend beyond the head or foot of the patient support table.
While pinion gear drive of a rack attached lengthwise under a patient table is satisfactory for some X-ray procedures, it does not meet the three above mentioned requirements firstly that the table travel nearly the full patient length, secondly that metallic parts of the drive be located outside the radiography zone, and thirdly that no drive parts extend beyond the head or foot ends of the patient table.
It is the object of the present invention to provide a radiographic support for a patient which meets the above three requirements.